scholarly journals The Oligopeptide Transport System Is Essential for the Development of Natural Competence in Streptococcus thermophilus Strain LMD-9

2009 ◽  
Vol 191 (14) ◽  
pp. 4647-4655 ◽  
Author(s):  
Rozenn Gardan ◽  
Colette Besset ◽  
Alain Guillot ◽  
Christophe Gitton ◽  
Véronique Monnet
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Thermophilus ◽  
Defined Medium ◽  
Mass Spectrometry Analysis ◽  
Transport Systems ◽  
Label Free ◽  
Spectrometry Analysis ◽  
Proteomic Approach ◽  
Liquid Chromatography Tandem Mass ◽  
Oligopeptide Transport

ABSTRACT In gram-positive bacteria, oligopeptide transport systems, called Opp or Ami, play a role in nutrition but are also involved in the internalization of signaling peptides that take part in the functioning of quorum-sensing pathways. Our objective was to reveal functions that are controlled by Ami via quorum-sensing mechanisms in Streptococcus thermophilus, a nonpathogenic bacterium widely used in dairy technology in association with other bacteria. Using a label-free proteomic approach combining one-dimensional electrophoresis with liquid chromatography-tandem mass spectrometry analysis, we compared the proteome of the S. thermophilus LMD-9 to that of a mutant deleted for the subunits C, D, and E of the ami operon. Both strains were grown in a chemically defined medium (CDM) without peptides. We focused our attention on proteins that were no more detected in the ami deletion mutant. In addition to the three subunits of the Ami transporter, 17 proteins fulfilled this criterion and, among them, 7 were similar to proteins that have been identified as essential for transformation in S. pneumoniae. These results led us to find a condition of growth, the early exponential state in CDM, that allows natural transformation in S. thermophilus LMD-9 to turn on spontaneously. Cells were not competent in M17 rich medium. Furthermore, we demonstrated that the Ami transporter controls the triggering of the competence state through the control of the transcription of comX, itself controlling the transcription of late competence genes. We also showed that one of the two oligopeptide-binding proteins of strain LMD-9 plays the predominant role in the control of competence.

scholarly journals Possible proteomic biomarkers for the detection of pancreatic cancer in oral fluids

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
O. Deutsch ◽  
Y. Haviv ◽  
G. Krief ◽  
N. Keshet ◽  
R. Westreich ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Pancreatic Cancer ◽  
Mass Spectrometry Analysis ◽  
Label Free ◽  
Two Dimensional Gel Electrophoresis ◽  
Spectrometry Analysis ◽  
Oral Fluids ◽  
Liquid Chromatography Tandem Mass ◽  
Differential Expression Profile ◽  
Auc Value

AbstractThe 80% mortality rate of pancreatic-cancer (PC) makes early diagnosis a challenge. Oral fluids (OF) may be considered the ultimate body fluid for non-invasive examinations. We have developed techniques to improve visualization of minor OF proteins thereby overcoming major barriers to using OF as a diagnostic fluid. The aim of this study was to establish a short discriminative panel of OF biomarkers for the detection of PC. Unstimulated OF were collected from PC patients and controls (n = 30). High-abundance-proteins were depleted and the remaining proteins were analyzed by two-dimensional-gel-electrophoresis and quantitative dimethylation-liquid-chromatography-tandem mass-spectrometry. Label-free quantitative-mass-spectrometry analysis (qMS) was performed on 20 individual samples (n = 20). More than 100 biomarker candidates were identified in OF samples, and 21 had a highly differential expression profile. qMS analysis yielded a ROC-plot AUC value of 0.91 with 90.0% sensitivity and specificity for a combination of five biomarker candidates. We found a combination of five biomarkers for PC. Most of these proteins are known to be related to PC or other gastric cancers, but have never been detected in OF. This study demonstrates the importance of novel OF depletion methodologies for increased protein visibility and highlights the clinical applicability of OF as a diagnostic fluid.

Coronatin-2 from the entomopathogenic fungus Conidiobolus coronatus kills Galleria mellonella larvae and incapacitates hemocytes

2016 ◽  
Vol 107 (1) ◽  
pp. 66-76 ◽  
Author(s):  
M.I. Boguś ◽  
W. Wieloch ◽  
M. Ligęza-Żuber
Keyword(s):  
Entomopathogenic Fungus ◽  
Galleria Mellonella ◽  
Elongation Factor ◽  
Peptide Sequence ◽  
Mass Spectrometry Analysis ◽  
Sequence Coverage ◽  
Spectrometry Analysis ◽  
Conidiobolus Coronatus ◽  
Liquid Chromatography Tandem Mass

AbstractCoronatin-2, a 14.5 kDa protein, was isolated from culture filtrates of the entomopathogenic fungus Conidiobolus coronatus (Costantin) Batko (Entomophthoramycota: Entomophthorales). After LC–MS/MS (liquid chromatography tandem mass spectrometry) analysis of the tryptic peptide digest of coronatin-2 and a mass spectra database search no orthologs of this protein could be found in fungi. The highest homology was observed to the partial translation elongation factor 1a from Sphaerosporium equinum (protein sequence coverage, 21%), with only one peptide sequence, suggesting that coronatin-2 is a novel fungal protein that has not yet been described. In contrast to coronatin-1, an insecticidal 36 kDa protein, which shows both elastolytic and chitinolytic activity, coronatin-2 showed no enzymatic activity. Addition of coronatin-2 into cultures of hemocytes taken from larvae of Galleria mellonella Linnaeus (Lepidoptera: Pyralidae), resulted in progressive disintegration of nets formed by granulocytes and plasmatocytes due to rapid degranulation of granulocytes, extensive vacuolization of plasmatocytes accompanied by cytoplasm expulsion, and cell disintegration. Spherulocytes remained intact, while oenocytes rapidly disintegrated. Coronatin-2 produced 80% mortality when injected into G. mellonella at 5 µg larva−1. Further study is warranted to determine the relevance of the acute toxicity of coronatin-2 and its effects on hemocytes in vitro to virulence of C. coronatus against its hosts.

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